Need help!
How recognize the mac addres ethernet shield?
I think you can just assign whatever mac address you want,
some ethernet shields have a number on the box/somewhere on the shield
but I will write mac addres ethernet shield or router???
Yes. You write the MAC address to the shield. See any of the Ethernet examples.
You have crossed it out with your red box
byte mac[] = { 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED };
Leo..
yes it's mac address is from standart example of arduino library
but why not ip in cmd???
The Ethernet library sends the IP address to the W5100 chip (via SPI) and reads it back from the chip. I suspect something is interfering with the SPI bus. Do you have an SD card in the SD slot of the Ethernet board? Try removing it. If that fixes the problem be sure to set Pin 4 (SD slave select) to HIGH in setup() before Ethernet.begin().
If you are wondering why you also have to set the MAC address on Arduino Ethernet shields, besides the IP address, it is because these chips do not have it embedded in the hardware like most PC network cards do, so it must be set via software.
Without getting into too much details, you can come up with a valid MAC address with 0xDE followed by 5 more random bytes. Just make sure you do not have duplicate MACs on your network, so use different addresses if you have multiple Arduinos connected to your network at the same time.
okey thnks all!